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Joshua Emery

A UT professor has helped detect water on Psyche, the largest metallic asteroid in the solar system. The asteroid is the target of a proposed NASA mission.

Joshua Emery, the Lawrence A. Taylor Associate Professor of Planetary Science, co-authored the study with Driss Takir, a US Geological Survey scientist based in Flagstaff, Arizona. Takir, who carried out the telescopic observations of the asteroid, earned his doctorate from the UT Department of Earth and Planetary Sciences and studied under Emery.

The study, published in the Astronomical Journal under the auspices of the US Geological Survey and NASA, provides evidence for water-rich minerals on Psyche.

Psyche is 186 miles across and is made of almost pure nickel-iron metal. It is thought to be the remnant core of a budding planet that was mostly destroyed by impacts billions of years ago. Previous observations of Psyche had shown no evidence of water-rich minerals on its surface. However, new observations from the NASA Infrared Telescope Facility in Hawaii show evidence of water or hydroxyl on its surface.

While the source of these molecules on Psyche remains a mystery, scientists propose a few possible mechanisms for its formation. It’s possible that water-rich minerals detected on Psyche might have been delivered by carbonaceous asteroids that impacted Psyche in the distant past.

Takir is a member of NASA’s OSIRIS-REx mission and the Japanese Aerospace Exploration Agency’s Hayabusa2 mission to collect carbonaceous samples from the water-rich asteroids Bennu and Ryugu. Emery also is part of the OSIRIS-REx project, the first US mission to collect a sample of an asteroid and return it to Earth for study.

Emery helped develop the goals and measurement requirements around which the mission has been designed. He leads a science team subgroup, the thermal analysis working group, that will examine measurements of heat emitted by the surface at different times of the day.


Lola Alapo (865-974-3993,